The present invention relates to a bracelet for moving sensors along a straight or elbow pipe, as used for measuring the thickness or another physical feature of the pipe with ultrasonic or other types of sensors.
Water pipes used in nuclear reactors are subject to long-term water flow corrosion and erosion problems, also known as xe2x80x9cFlow Assisted Corrosionxe2x80x9d. These problems lead to thinning of the pipes and ultimately to their bursting. Regular preventive inspections must therefore be carried out in order to detect any thinning in the pipes. The bent sections of the pipes are especially vulnerable to this type of corrosion, but are difficult to inspect. Also, pipes in nuclear reactors are hard to reach in cramped locations.
Known devices used to measure thickness of these pipes are ill-equipped to provide accurate readings. Furthermore, these are cumbersome and difficult to operate.
Known in the art, there is the bracelet used by the Specialized Inspection and Maintenance Department xe2x80x9cSIMDxe2x80x9d of Hydro Ontario. The xe2x80x9cSIMDxe2x80x9d bracelet has a mid grasping portion and side pivoting legs attached to the mid grasping portion. The side pivoting legs contain supports housing only a few ultrasonic sensors. An encoder is mounted in the center of the mid grasping part. Small magnets are used to maintain the supports in contact with the surface of a pipe. A curved flexible rod is attached at side edges of the pivoting legs to maintain these in an open biased position.
To use the xe2x80x9cSIMDxe2x80x9d bracelet, a user has to manually force the legs against a pipe to be inspected. The inspection of the pipe is done in three (3) distinct passes, which are spaced-apart by about 30xc2x0 each since the bracelet discontinously covers less than half the pipe""s circumference. The passes are then combined by a software program, which provides an image of the inspected pipe. The xe2x80x9cSIMDxe2x80x9d bracelet requires great dexterity from the operator to ensure that all three (3) passes are perfectly aligned.
Known in the art are U.S. Pat. No. 5,174,155 (SUGIMOTO); U.S. Pat. No. 4,375,165 (DE STERKE); U.S. Pat. No. 3,602,036 (PETERSON); U.S. Pat. No. 3,921,440 (TOTH); U.S. Pat. No. 5,585,565 (GLASCOCK, et al.); U.S. Pat. No. 5,619,423 (SCRANTZ); U.S. Pat. No. 5,583,292 (KARBACH et al.); U.S. Pat. No. 6,003,377 (WAAG et al.); U.S. Pat. No. 5,963,030 (STARK); U.S. Pat. No. 4,586,379 (BURCKHARDT, Jr.); U.S. Pat. No. 4,467,654 (MURAKAMI et al.); U.S. Pat. No. 5,359,897 (HAMSTEAD et al.); U.S. Pat. No. 5,313,837 (HAYNES); U.S. Pat. No. 4,307,616 (VASILE); U.S. Pat. No. 5,438,872 (KOBAYASHI et al.); U.S. Pat. No. 4,679,437 (KOIKE et al.); U.S. Pat. No. 4,312,230 (BRICKER et al.); U.S. Pat. No. 5,756,898 (DIATSCHENKO et al.); U.S. Pat. No. 6,000,288 (KWUN et al.); U.S. Pat. No. 4,285,242 (BRAITHWAITE); U.S. Pat. No. 4,117,733 (GUGEL); U.S. Pat. No. 5,770,800 (JENKINS et al.); U.S. Pat. No. 4,295,092 (OKAMURA); U.S. Pat. No. 5,138,644 (McARDLE et al.); U.S. Pat. No. 5,965,818 (WANG); U.S. Pat. No. 4,922,748 (HOPENFELD); and U.S. Pat. No. 4,779,453 (HOPENFELD), which show various devices for pipe inspection, but are all poorly or simply not adequate for inspecting the thickness of a pipe with elbow sections.
An object of the present invention is to provide a bracelet for moving sensors along a pipe, as used for measuring the thickness or another physical feature of the pipe, and which is adapted to bent or elbow pipes and is easy to use even in cramped spaces and does not suffer from the drawbacks of the prior art.
Another object of the invention is to provide such a bracelet, which allows for a coherent and continuous inspection of a pipe having elbow sections or not.
Another object of the invention is to provide such a bracelet, which can maintain the spacing between the ultrasonic sensors while following the surface to be inspected for good contact between the sensors and the pipe.
According to the present invention, there is provided a bracelet for moving sensors along a pipe, comprising:
a number of side-by-side positionable supports for removably holding the sensors respectively;
a flexible attachment for holding the supports in a pliant side-by-side series arrangement, the attachment having opposite ends extending beyond the supports at opposite ends of the series arrangement; and
a frame having an inner circular opened surface for installation around the pipe, and a longitudinal circular side receiving surface along which the series arrangement of the supports is mounted, the side receiving surface being provided a with fastening members projecting at both ends of the series arrangement of the supports, the ends of the attachment being supported by the fastening members.
Preferably, when the sensors are ultrasonic sensors, each support has a coupling liquid channel with a bottom opening extending under the sensor held by the support.
Preferably, the flexible attachment is fastened to the frame by means of an elastic strap extending over the supports and urging them against the pipe for better contact therewith.
With the above bracelet, pipes with elbow sections can be inspected in a single continous pass, with a minimum of training required from the operator/user, and without dismantling the pipe.